1. Field of the Invention
The present invention relates to an image forming apparatus including a blower unit.
2. Description of the Related Art
Hitherto, as image forming apparatus of the electrophotographic type, there are known a copying machine, a printer, and a facsimile. In the image forming apparatus, a sheet on which a developer image is formed with a developer such as toner is nipped and conveyed by a fixing roller pair including a heating roller and a pressurizing roller of a fixing device, thereby heating and pressurizing the sheet to fix the developer image to the sheet.
In this image forming apparatus, when a sheet narrower than the maximum width of the fixing roller pair of the fixing device is nipped and conveyed, in a region of the fixing roller pair in which the sheet does not pass, heat is not absorbed by the sheet, and the temperature in the region becomes higher than the temperature in a region in which the sheet passes, resulting in a non-uniform temperature distribution. To address this problem, in U.S. Pat. No. 7,623,822, in order to attain a uniform temperature distribution of the fixing roller pair, a fan configured to cool the fixing roller pair is controlled, depending on the width of the sheet.
Moreover, when sheets on which images are formed are discharged and stacked while the sheets are hot, the stacked sheets may be stuck on one another by fused developer. When the sheets stuck on one another are separated, images formed on the sheets and the sheets may be damaged. To address this problem, in Japanese Patent Application Laid-Open No. 2014-126763, air is blown from a fan to a sheet that has been heated and pressurized by a fixing device, thereby cooling the sheet.
However, when moisture contained in the sheet is vaporized when the sheet is heated during the fixing, air around the fixing device is humidified. If the humid air is moved by the airflow of the fan to the neighborhood of a laser scanner serving as an exposure device in the image forming apparatus, there is a problem that dew condensation occurs on the laser scanner, depending on an environment around the image forming apparatus.
When the dew condensation occurs particularly on a laser emission portion of the laser scanner, the laser scanner may not output the light intensity required for forming an electrostatic latent image on a photosensitive drum serving as an image bearing member, and a failure may occur during the image formation.